The structure of this invention lies in the field of storm windows and is directed to such windows which are very low in first cost and are very light and easy to install and remove. It is more particularly directed to such windows which may be installed in window frames of a house interiorly of the existing window closures, do not need fasteners fixed to the window frames, and may be stored in minimal space when not in use.
Storm windows are commonly used in all of the colder parts of the country for the purpose of providing a dead air space between the storm window and the existing window closure which serves as insulation to reduce the amount of heat lost to the exterior during winter months. At the present time the cost and the shortage of heating energy supplies has greatly increased the need for such insulation protection.
Conventional storm windows generally consist of wood or metal frames glazed with single panes of glass or relatively thick rigid plastic, the windows being mounted exteriorly of the house on hooks at the upper sides of the window frames, and one or more hooks at the lower end of the window can be fastened to eyes on the window sills from the interior. Release of the lower hooks allows the storm windows to be pivoted outward about the upper fasteners to air out the rooms on occasion. These windows are rigid and heavy and are difficult and sometimes dangerous to install and remove, particularly on windows of the upper floors. Moreover, they are very bulky and require a great deal of storage space when not in use.
In order to improve the insulating effect some storm windows have been double glazed, providing a dead air space between the two panes in addition to the dead air space between the storm window and the normal house window. This is useful but also very expensive because it requires twice as much glass and special frames. Also, such a window is much heavier and consequently more difficult to manipulate.
In the field of mounting techiques it has been proposed to surround the periphery of a storm window pane with a length of tubing which is inflatable to enlarge its periphery and hold it in frictional engagement with a window frame. While this proposal has merit, it calls for a heavy and rather expensive extrusion of rubber or the like which must have a tubular passage, spaced fins to receive the pane, and ribs extending outward to engage a window frame. In addition it requires considerable storage space when not in use.
One proposal for a relatively cheap storm window calls for a sheet of rigid plastic material provided with integral hook-like projections for attaching it to an existing window screen. The fastening means is not too satisfactory, and window screens are usually rather loose fits so that a good deal of air leakage occurs, reducing the insulation value to a marked degree. Also, the unit cannot be collapsed in any way for convenient storage. It does not provide a double pane insulation feature, and if it were built as a double pane unit it would be very costly.